: : Nick, your answer to the question doesn't make sense to me. If the heater sets all night, the water should be as hot as the thermostat is set to. What he is saying is that after all night the water is not hot but after running the water for a time, it now begins to heat. I am having a similar problem on an intermittent basis with my heater. Usually it is fine, but sometimes the water is barely warm even though it has not be used for hours. Then for some unexplained reason, it heats normally again.: Gary hit the nail on the head. I have the exact problem he is describing.I would suggest checking (or replacing)the Thermostat (faulty contact.) It may just be the culprit. Hube